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1 <section id="control">
2 <title>User Controls</title>
3
4 <para>Devices typically have a number of user-settable controls
5such as brightness, saturation and so on, which would be presented to
6the user on a graphical user interface. But, different devices
7will have different controls available, and furthermore, the range of
8possible values, and the default value will vary from device to
9device. The control ioctls provide the information and a mechanism to
10create a nice user interface for these controls that will work
11correctly with any device.</para>
12
13 <para>All controls are accessed using an ID value. V4L2 defines
14several IDs for specific purposes. Drivers can also implement their
15own custom controls using <constant>V4L2_CID_PRIVATE_BASE</constant>
16and higher values. The pre-defined control IDs have the prefix
17<constant>V4L2_CID_</constant>, and are listed in <xref
18linkend="control-id" />. The ID is used when querying the attributes of
19a control, and when getting or setting the current value.</para>
20
21 <para>Generally applications should present controls to the user
22without assumptions about their purpose. Each control comes with a
23name string the user is supposed to understand. When the purpose is
24non-intuitive the driver writer should provide a user manual, a user
25interface plug-in or a driver specific panel application. Predefined
26IDs were introduced to change a few controls programmatically, for
27example to mute a device during a channel switch.</para>
28
29 <para>Drivers may enumerate different controls after switching
30the current video input or output, tuner or modulator, or audio input
31or output. Different in the sense of other bounds, another default and
32current value, step size or other menu items. A control with a certain
33<emphasis>custom</emphasis> ID can also change name and
34type.<footnote>
35 <para>It will be more convenient for applications if drivers
36make use of the <constant>V4L2_CTRL_FLAG_DISABLED</constant> flag, but
37that was never required.</para>
38 </footnote> Control values are stored globally, they do not
39change when switching except to stay within the reported bounds. They
40also do not change &eg; when the device is opened or closed, when the
41tuner radio frequency is changed or generally never without
42application request. Since V4L2 specifies no event mechanism, panel
43applications intended to cooperate with other panel applications (be
44they built into a larger application, as a TV viewer) may need to
45regularly poll control values to update their user
46interface.<footnote>
47 <para>Applications could call an ioctl to request events.
48After another process called &VIDIOC-S-CTRL; or another ioctl changing
49shared properties the &func-select; function would indicate
50readability until any ioctl (querying the properties) is
51called.</para>
52 </footnote></para>
53
54 <table pgwide="1" frame="none" id="control-id">
55 <title>Control IDs</title>
56 <tgroup cols="3">
57 &cs-def;
58 <thead>
59 <row>
60 <entry>ID</entry>
61 <entry>Type</entry>
62 <entry>Description</entry>
63 </row>
64 </thead>
65 <tbody valign="top">
66 <row>
67 <entry><constant>V4L2_CID_BASE</constant></entry>
68 <entry></entry>
69 <entry>First predefined ID, equal to
70<constant>V4L2_CID_BRIGHTNESS</constant>.</entry>
71 </row>
72 <row>
73 <entry><constant>V4L2_CID_USER_BASE</constant></entry>
74 <entry></entry>
75 <entry>Synonym of <constant>V4L2_CID_BASE</constant>.</entry>
76 </row>
77 <row>
78 <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry>
79 <entry>integer</entry>
80 <entry>Picture brightness, or more precisely, the black
81level.</entry>
82 </row>
83 <row>
84 <entry><constant>V4L2_CID_CONTRAST</constant></entry>
85 <entry>integer</entry>
86 <entry>Picture contrast or luma gain.</entry>
87 </row>
88 <row>
89 <entry><constant>V4L2_CID_SATURATION</constant></entry>
90 <entry>integer</entry>
91 <entry>Picture color saturation or chroma gain.</entry>
92 </row>
93 <row>
94 <entry><constant>V4L2_CID_HUE</constant></entry>
95 <entry>integer</entry>
96 <entry>Hue or color balance.</entry>
97 </row>
98 <row>
99 <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry>
100 <entry>integer</entry>
101 <entry>Overall audio volume. Note some drivers also
102provide an OSS or ALSA mixer interface.</entry>
103 </row>
104 <row>
105 <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry>
106 <entry>integer</entry>
107 <entry>Audio stereo balance. Minimum corresponds to all
108the way left, maximum to right.</entry>
109 </row>
110 <row>
111 <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry>
112 <entry>integer</entry>
113 <entry>Audio bass adjustment.</entry>
114 </row>
115 <row>
116 <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry>
117 <entry>integer</entry>
118 <entry>Audio treble adjustment.</entry>
119 </row>
120 <row>
121 <entry><constant>V4L2_CID_AUDIO_MUTE</constant></entry>
122 <entry>boolean</entry>
123 <entry>Mute audio, &ie; set the volume to zero, however
124without affecting <constant>V4L2_CID_AUDIO_VOLUME</constant>. Like
125ALSA drivers, V4L2 drivers must mute at load time to avoid excessive
126noise. Actually the entire device should be reset to a low power
127consumption state.</entry>
128 </row>
129 <row>
130 <entry><constant>V4L2_CID_AUDIO_LOUDNESS</constant></entry>
131 <entry>boolean</entry>
132 <entry>Loudness mode (bass boost).</entry>
133 </row>
134 <row>
135 <entry><constant>V4L2_CID_BLACK_LEVEL</constant></entry>
136 <entry>integer</entry>
137 <entry>Another name for brightness (not a synonym of
138<constant>V4L2_CID_BRIGHTNESS</constant>). This control is deprecated
139and should not be used in new drivers and applications.</entry>
140 </row>
141 <row>
142 <entry><constant>V4L2_CID_AUTO_WHITE_BALANCE</constant></entry>
143 <entry>boolean</entry>
144 <entry>Automatic white balance (cameras).</entry>
145 </row>
146 <row>
147 <entry><constant>V4L2_CID_DO_WHITE_BALANCE</constant></entry>
148 <entry>button</entry>
149 <entry>This is an action control. When set (the value is
150ignored), the device will do a white balance and then hold the current
151setting. Contrast this with the boolean
152<constant>V4L2_CID_AUTO_WHITE_BALANCE</constant>, which, when
153activated, keeps adjusting the white balance.</entry>
154 </row>
155 <row>
156 <entry><constant>V4L2_CID_RED_BALANCE</constant></entry>
157 <entry>integer</entry>
158 <entry>Red chroma balance.</entry>
159 </row>
160 <row>
161 <entry><constant>V4L2_CID_BLUE_BALANCE</constant></entry>
162 <entry>integer</entry>
163 <entry>Blue chroma balance.</entry>
164 </row>
165 <row>
166 <entry><constant>V4L2_CID_GAMMA</constant></entry>
167 <entry>integer</entry>
168 <entry>Gamma adjust.</entry>
169 </row>
170 <row>
171 <entry><constant>V4L2_CID_WHITENESS</constant></entry>
172 <entry>integer</entry>
173 <entry>Whiteness for grey-scale devices. This is a synonym
174for <constant>V4L2_CID_GAMMA</constant>. This control is deprecated
175and should not be used in new drivers and applications.</entry>
176 </row>
177 <row>
178 <entry><constant>V4L2_CID_EXPOSURE</constant></entry>
179 <entry>integer</entry>
180 <entry>Exposure (cameras). [Unit?]</entry>
181 </row>
182 <row>
183 <entry><constant>V4L2_CID_AUTOGAIN</constant></entry>
184 <entry>boolean</entry>
185 <entry>Automatic gain/exposure control.</entry>
186 </row>
187 <row>
188 <entry><constant>V4L2_CID_GAIN</constant></entry>
189 <entry>integer</entry>
190 <entry>Gain control.</entry>
191 </row>
192 <row>
193 <entry><constant>V4L2_CID_HFLIP</constant></entry>
194 <entry>boolean</entry>
195 <entry>Mirror the picture horizontally.</entry>
196 </row>
197 <row>
198 <entry><constant>V4L2_CID_VFLIP</constant></entry>
199 <entry>boolean</entry>
200 <entry>Mirror the picture vertically.</entry>
201 </row>
202 <row>
203 <entry><constant>V4L2_CID_HCENTER_DEPRECATED</constant> (formerly <constant>V4L2_CID_HCENTER</constant>)</entry>
204 <entry>integer</entry>
205 <entry>Horizontal image centering. This control is
206deprecated. New drivers and applications should use the <link
207linkend="camera-controls">Camera class controls</link>
208<constant>V4L2_CID_PAN_ABSOLUTE</constant>,
209<constant>V4L2_CID_PAN_RELATIVE</constant> and
210<constant>V4L2_CID_PAN_RESET</constant> instead.</entry>
211 </row>
212 <row>
213 <entry><constant>V4L2_CID_VCENTER_DEPRECATED</constant>
214 (formerly <constant>V4L2_CID_VCENTER</constant>)</entry>
215 <entry>integer</entry>
216 <entry>Vertical image centering. Centering is intended to
217<emphasis>physically</emphasis> adjust cameras. For image cropping see
218<xref linkend="crop" />, for clipping <xref linkend="overlay" />. This
219control is deprecated. New drivers and applications should use the
220<link linkend="camera-controls">Camera class controls</link>
221<constant>V4L2_CID_TILT_ABSOLUTE</constant>,
222<constant>V4L2_CID_TILT_RELATIVE</constant> and
223<constant>V4L2_CID_TILT_RESET</constant> instead.</entry>
224 </row>
225 <row id="v4l2-power-line-frequency">
226 <entry><constant>V4L2_CID_POWER_LINE_FREQUENCY</constant></entry>
227 <entry>enum</entry>
228 <entry>Enables a power line frequency filter to avoid
229flicker. Possible values for <constant>enum v4l2_power_line_frequency</constant> are:
230<constant>V4L2_CID_POWER_LINE_FREQUENCY_DISABLED</constant> (0),
231<constant>V4L2_CID_POWER_LINE_FREQUENCY_50HZ</constant> (1) and
232<constant>V4L2_CID_POWER_LINE_FREQUENCY_60HZ</constant> (2).</entry>
233 </row>
234 <row>
235 <entry><constant>V4L2_CID_HUE_AUTO</constant></entry>
236 <entry>boolean</entry>
237 <entry>Enables automatic hue control by the device. The
238effect of setting <constant>V4L2_CID_HUE</constant> while automatic
239hue control is enabled is undefined, drivers should ignore such
240request.</entry>
241 </row>
242 <row>
243 <entry><constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant></entry>
244 <entry>integer</entry>
245 <entry>This control specifies the white balance settings
246as a color temperature in Kelvin. A driver should have a minimum of
2472800 (incandescent) to 6500 (daylight). For more information about
248color temperature see <ulink
249url="http://en.wikipedia.org/wiki/Color_temperature">Wikipedia</ulink>.</entry>
250 </row>
251 <row>
252 <entry><constant>V4L2_CID_SHARPNESS</constant></entry>
253 <entry>integer</entry>
254 <entry>Adjusts the sharpness filters in a camera. The
255minimum value disables the filters, higher values give a sharper
256picture.</entry>
257 </row>
258 <row>
259 <entry><constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant></entry>
260 <entry>integer</entry>
261 <entry>Adjusts the backlight compensation in a camera. The
262minimum value disables backlight compensation.</entry>
263 </row>
264 <row>
265 <entry><constant>V4L2_CID_CHROMA_AGC</constant></entry>
266 <entry>boolean</entry>
267 <entry>Chroma automatic gain control.</entry>
268 </row>
269 <row>
270 <entry><constant>V4L2_CID_COLOR_KILLER</constant></entry>
271 <entry>boolean</entry>
272 <entry>Enable the color killer (&ie; force a black &amp; white image in case of a weak video signal).</entry>
273 </row>
274 <row id="v4l2-colorfx">
275 <entry><constant>V4L2_CID_COLORFX</constant></entry>
276 <entry>enum</entry>
277 <entry>Selects a color effect. Possible values for
278<constant>enum v4l2_colorfx</constant> are:
279<constant>V4L2_COLORFX_NONE</constant> (0),
280<constant>V4L2_COLORFX_BW</constant> (1) and
281<constant>V4L2_COLORFX_SEPIA</constant> (2).</entry>
282 </row>
283 <row>
284 <entry><constant>V4L2_CID_LASTP1</constant></entry>
285 <entry></entry>
286 <entry>End of the predefined control IDs (currently
287<constant>V4L2_CID_COLORFX</constant> + 1).</entry>
288 </row>
289 <row>
290 <entry><constant>V4L2_CID_PRIVATE_BASE</constant></entry>
291 <entry></entry>
292 <entry>ID of the first custom (driver specific) control.
293Applications depending on particular custom controls should check the
294driver name and version, see <xref linkend="querycap" />.</entry>
295 </row>
296 </tbody>
297 </tgroup>
298 </table>
299
300 <para>Applications can enumerate the available controls with the
301&VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls, get and set a
302control value with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls.
303Drivers must implement <constant>VIDIOC_QUERYCTRL</constant>,
304<constant>VIDIOC_G_CTRL</constant> and
305<constant>VIDIOC_S_CTRL</constant> when the device has one or more
306controls, <constant>VIDIOC_QUERYMENU</constant> when it has one or
307more menu type controls.</para>
308
309 <example>
310 <title>Enumerating all controls</title>
311
312 <programlisting>
313&v4l2-queryctrl; queryctrl;
314&v4l2-querymenu; querymenu;
315
316static void
317enumerate_menu (void)
318{
319 printf (" Menu items:\n");
320
321 memset (&amp;querymenu, 0, sizeof (querymenu));
322 querymenu.id = queryctrl.id;
323
324 for (querymenu.index = queryctrl.minimum;
325 querymenu.index &lt;= queryctrl.maximum;
326 querymenu.index++) {
327 if (0 == ioctl (fd, &VIDIOC-QUERYMENU;, &amp;querymenu)) {
328 printf (" %s\n", querymenu.name);
329 } else {
330 perror ("VIDIOC_QUERYMENU");
331 exit (EXIT_FAILURE);
332 }
333 }
334}
335
336memset (&amp;queryctrl, 0, sizeof (queryctrl));
337
338for (queryctrl.id = V4L2_CID_BASE;
339 queryctrl.id &lt; V4L2_CID_LASTP1;
340 queryctrl.id++) {
341 if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
342 if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED)
343 continue;
344
345 printf ("Control %s\n", queryctrl.name);
346
347 if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
348 enumerate_menu ();
349 } else {
350 if (errno == EINVAL)
351 continue;
352
353 perror ("VIDIOC_QUERYCTRL");
354 exit (EXIT_FAILURE);
355 }
356}
357
358for (queryctrl.id = V4L2_CID_PRIVATE_BASE;;
359 queryctrl.id++) {
360 if (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
361 if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED)
362 continue;
363
364 printf ("Control %s\n", queryctrl.name);
365
366 if (queryctrl.type == V4L2_CTRL_TYPE_MENU)
367 enumerate_menu ();
368 } else {
369 if (errno == EINVAL)
370 break;
371
372 perror ("VIDIOC_QUERYCTRL");
373 exit (EXIT_FAILURE);
374 }
375}
376</programlisting>
377 </example>
378
379 <example>
380 <title>Changing controls</title>
381
382 <programlisting>
383&v4l2-queryctrl; queryctrl;
384&v4l2-control; control;
385
386memset (&amp;queryctrl, 0, sizeof (queryctrl));
387queryctrl.id = V4L2_CID_BRIGHTNESS;
388
389if (-1 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;queryctrl)) {
390 if (errno != EINVAL) {
391 perror ("VIDIOC_QUERYCTRL");
392 exit (EXIT_FAILURE);
393 } else {
394 printf ("V4L2_CID_BRIGHTNESS is not supported\n");
395 }
396} else if (queryctrl.flags &amp; V4L2_CTRL_FLAG_DISABLED) {
397 printf ("V4L2_CID_BRIGHTNESS is not supported\n");
398} else {
399 memset (&amp;control, 0, sizeof (control));
400 control.id = V4L2_CID_BRIGHTNESS;
401 control.value = queryctrl.default_value;
402
403 if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &amp;control)) {
404 perror ("VIDIOC_S_CTRL");
405 exit (EXIT_FAILURE);
406 }
407}
408
409memset (&amp;control, 0, sizeof (control));
410control.id = V4L2_CID_CONTRAST;
411
412if (0 == ioctl (fd, &VIDIOC-G-CTRL;, &amp;control)) {
413 control.value += 1;
414
415 /* The driver may clamp the value or return ERANGE, ignored here */
416
417 if (-1 == ioctl (fd, &VIDIOC-S-CTRL;, &amp;control)
418 &amp;&amp; errno != ERANGE) {
419 perror ("VIDIOC_S_CTRL");
420 exit (EXIT_FAILURE);
421 }
422/* Ignore if V4L2_CID_CONTRAST is unsupported */
423} else if (errno != EINVAL) {
424 perror ("VIDIOC_G_CTRL");
425 exit (EXIT_FAILURE);
426}
427
428control.id = V4L2_CID_AUDIO_MUTE;
429control.value = TRUE; /* silence */
430
431/* Errors ignored */
432ioctl (fd, VIDIOC_S_CTRL, &amp;control);
433</programlisting>
434 </example>
435 </section>
436
437 <section id="extended-controls">
438 <title>Extended Controls</title>
439
440 <section>
441 <title>Introduction</title>
442
443 <para>The control mechanism as originally designed was meant
444to be used for user settings (brightness, saturation, etc). However,
445it turned out to be a very useful model for implementing more
446complicated driver APIs where each driver implements only a subset of
447a larger API.</para>
448
449 <para>The MPEG encoding API was the driving force behind
450designing and implementing this extended control mechanism: the MPEG
451standard is quite large and the currently supported hardware MPEG
452encoders each only implement a subset of this standard. Further more,
453many parameters relating to how the video is encoded into an MPEG
454stream are specific to the MPEG encoding chip since the MPEG standard
455only defines the format of the resulting MPEG stream, not how the
456video is actually encoded into that format.</para>
457
458 <para>Unfortunately, the original control API lacked some
459features needed for these new uses and so it was extended into the
460(not terribly originally named) extended control API.</para>
461
462 <para>Even though the MPEG encoding API was the first effort
463to use the Extended Control API, nowadays there are also other classes
464of Extended Controls, such as Camera Controls and FM Transmitter Controls.
465The Extended Controls API as well as all Extended Controls classes are
466described in the following text.</para>
467 </section>
468
469 <section>
470 <title>The Extended Control API</title>
471
472 <para>Three new ioctls are available: &VIDIOC-G-EXT-CTRLS;,
473&VIDIOC-S-EXT-CTRLS; and &VIDIOC-TRY-EXT-CTRLS;. These ioctls act on
474arrays of controls (as opposed to the &VIDIOC-G-CTRL; and
475&VIDIOC-S-CTRL; ioctls that act on a single control). This is needed
476since it is often required to atomically change several controls at
477once.</para>
478
479 <para>Each of the new ioctls expects a pointer to a
480&v4l2-ext-controls;. This structure contains a pointer to the control
481array, a count of the number of controls in that array and a control
482class. Control classes are used to group similar controls into a
483single class. For example, control class
484<constant>V4L2_CTRL_CLASS_USER</constant> contains all user controls
485(&ie; all controls that can also be set using the old
486<constant>VIDIOC_S_CTRL</constant> ioctl). Control class
487<constant>V4L2_CTRL_CLASS_MPEG</constant> contains all controls
488relating to MPEG encoding, etc.</para>
489
490 <para>All controls in the control array must belong to the
491specified control class. An error is returned if this is not the
492case.</para>
493
494 <para>It is also possible to use an empty control array (count
495== 0) to check whether the specified control class is
496supported.</para>
497
498 <para>The control array is a &v4l2-ext-control; array. The
499<structname>v4l2_ext_control</structname> structure is very similar to
500&v4l2-control;, except for the fact that it also allows for 64-bit
501values and pointers to be passed.</para>
502
503 <para>It is important to realize that due to the flexibility of
504controls it is necessary to check whether the control you want to set
505actually is supported in the driver and what the valid range of values
506is. So use the &VIDIOC-QUERYCTRL; and &VIDIOC-QUERYMENU; ioctls to
507check this. Also note that it is possible that some of the menu
508indices in a control of type <constant>V4L2_CTRL_TYPE_MENU</constant>
509may not be supported (<constant>VIDIOC_QUERYMENU</constant> will
510return an error). A good example is the list of supported MPEG audio
511bitrates. Some drivers only support one or two bitrates, others
512support a wider range.</para>
513 </section>
514
515 <section>
516 <title>Enumerating Extended Controls</title>
517
518 <para>The recommended way to enumerate over the extended
519controls is by using &VIDIOC-QUERYCTRL; in combination with the
520<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag:</para>
521
522 <informalexample>
523 <programlisting>
524&v4l2-queryctrl; qctrl;
525
526qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
527while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;qctrl)) {
528 /* ... */
529 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
530}
531</programlisting>
532 </informalexample>
533
534 <para>The initial control ID is set to 0 ORed with the
535<constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant> flag. The
536<constant>VIDIOC_QUERYCTRL</constant> ioctl will return the first
537control with a higher ID than the specified one. When no such controls
538are found an error is returned.</para>
539
540 <para>If you want to get all controls within a specific control
541class, then you can set the initial
542<structfield>qctrl.id</structfield> value to the control class and add
543an extra check to break out of the loop when a control of another
544control class is found:</para>
545
546 <informalexample>
547 <programlisting>
548qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
549while (0 == ioctl (fd, &VIDIOC-QUERYCTRL;, &amp;qctrl)) {
550 if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG)
551 break;
552 /* ... */
553 qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
554 }
555</programlisting>
556 </informalexample>
557
558 <para>The 32-bit <structfield>qctrl.id</structfield> value is
559subdivided into three bit ranges: the top 4 bits are reserved for
560flags (&eg; <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>) and are not
561actually part of the ID. The remaining 28 bits form the control ID, of
562which the most significant 12 bits define the control class and the
563least significant 16 bits identify the control within the control
564class. It is guaranteed that these last 16 bits are always non-zero
565for controls. The range of 0x1000 and up are reserved for
566driver-specific controls. The macro
567<constant>V4L2_CTRL_ID2CLASS(id)</constant> returns the control class
568ID based on a control ID.</para>
569
570 <para>If the driver does not support extended controls, then
571<constant>VIDIOC_QUERYCTRL</constant> will fail when used in
572combination with <constant>V4L2_CTRL_FLAG_NEXT_CTRL</constant>. In
573that case the old method of enumerating control should be used (see
5741.8). But if it is supported, then it is guaranteed to enumerate over
575all controls, including driver-private controls.</para>
576 </section>
577
578 <section>
579 <title>Creating Control Panels</title>
580
581 <para>It is possible to create control panels for a graphical
582user interface where the user can select the various controls.
583Basically you will have to iterate over all controls using the method
584described above. Each control class starts with a control of type
585<constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant>.
586<constant>VIDIOC_QUERYCTRL</constant> will return the name of this
587control class which can be used as the title of a tab page within a
588control panel.</para>
589
590 <para>The flags field of &v4l2-queryctrl; also contains hints on
591the behavior of the control. See the &VIDIOC-QUERYCTRL; documentation
592for more details.</para>
593 </section>
594
595 <section id="mpeg-controls">
596 <title>MPEG Control Reference</title>
597
598 <para>Below all controls within the MPEG control class are
599described. First the generic controls, then controls specific for
600certain hardware.</para>
601
602 <section>
603 <title>Generic MPEG Controls</title>
604
605 <table pgwide="1" frame="none" id="mpeg-control-id">
606 <title>MPEG Control IDs</title>
607 <tgroup cols="4">
608 <colspec colname="c1" colwidth="1*" />
609 <colspec colname="c2" colwidth="6*" />
610 <colspec colname="c3" colwidth="2*" />
611 <colspec colname="c4" colwidth="6*" />
612 <spanspec namest="c1" nameend="c2" spanname="id" />
613 <spanspec namest="c2" nameend="c4" spanname="descr" />
614 <thead>
615 <row>
616 <entry spanname="id" align="left">ID</entry>
617 <entry align="left">Type</entry>
618 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
619 </row>
620 </thead>
621 <tbody valign="top">
622 <row><entry></entry></row>
623 <row>
624 <entry spanname="id"><constant>V4L2_CID_MPEG_CLASS</constant>&nbsp;</entry>
625 <entry>class</entry>
626 </row><row><entry spanname="descr">The MPEG class
627descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
628description of this control class. This description can be used as the
629caption of a Tab page in a GUI, for example.</entry>
630 </row>
631 <row><entry></entry></row>
632 <row id="v4l2-mpeg-stream-type">
633 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_TYPE</constant>&nbsp;</entry>
634 <entry>enum&nbsp;v4l2_mpeg_stream_type</entry>
635 </row><row><entry spanname="descr">The MPEG-1, -2 or -4
636output stream type. One cannot assume anything here. Each hardware
637MPEG encoder tends to support different subsets of the available MPEG
638stream types. The currently defined stream types are:</entry>
639 </row>
640 <row>
641 <entrytbl spanname="descr" cols="2">
642 <tbody valign="top">
643 <row>
644 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_PS</constant>&nbsp;</entry>
645 <entry>MPEG-2 program stream</entry>
646 </row>
647 <row>
648 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_TS</constant>&nbsp;</entry>
649 <entry>MPEG-2 transport stream</entry>
650 </row>
651 <row>
652 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_SS</constant>&nbsp;</entry>
653 <entry>MPEG-1 system stream</entry>
654 </row>
655 <row>
656 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_DVD</constant>&nbsp;</entry>
657 <entry>MPEG-2 DVD-compatible stream</entry>
658 </row>
659 <row>
660 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG1_VCD</constant>&nbsp;</entry>
661 <entry>MPEG-1 VCD-compatible stream</entry>
662 </row>
663 <row>
664 <entry><constant>V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD</constant>&nbsp;</entry>
665 <entry>MPEG-2 SVCD-compatible stream</entry>
666 </row>
667 </tbody>
668 </entrytbl>
669 </row>
670 <row><entry></entry></row>
671 <row>
672 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PMT</constant>&nbsp;</entry>
673 <entry>integer</entry>
674 </row><row><entry spanname="descr">Program Map Table
675Packet ID for the MPEG transport stream (default 16)</entry>
676 </row>
677 <row><entry></entry></row>
678 <row>
679 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_AUDIO</constant>&nbsp;</entry>
680 <entry>integer</entry>
681 </row><row><entry spanname="descr">Audio Packet ID for
682the MPEG transport stream (default 256)</entry>
683 </row>
684 <row><entry></entry></row>
685 <row>
686 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_VIDEO</constant>&nbsp;</entry>
687 <entry>integer</entry>
688 </row><row><entry spanname="descr">Video Packet ID for
689the MPEG transport stream (default 260)</entry>
690 </row>
691 <row><entry></entry></row>
692 <row>
693 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PID_PCR</constant>&nbsp;</entry>
694 <entry>integer</entry>
695 </row><row><entry spanname="descr">Packet ID for the
696MPEG transport stream carrying PCR fields (default 259)</entry>
697 </row>
698 <row><entry></entry></row>
699 <row>
700 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_AUDIO</constant>&nbsp;</entry>
701 <entry>integer</entry>
702 </row><row><entry spanname="descr">Audio ID for MPEG
703PES</entry>
704 </row>
705 <row><entry></entry></row>
706 <row>
707 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_PES_ID_VIDEO</constant>&nbsp;</entry>
708 <entry>integer</entry>
709 </row><row><entry spanname="descr">Video ID for MPEG
710PES</entry>
711 </row>
712 <row><entry></entry></row>
713 <row id="v4l2-mpeg-stream-vbi-fmt">
714 <entry spanname="id"><constant>V4L2_CID_MPEG_STREAM_VBI_FMT</constant>&nbsp;</entry>
715 <entry>enum&nbsp;v4l2_mpeg_stream_vbi_fmt</entry>
716 </row><row><entry spanname="descr">Some cards can embed
717VBI data (&eg; Closed Caption, Teletext) into the MPEG stream. This
718control selects whether VBI data should be embedded, and if so, what
719embedding method should be used. The list of possible VBI formats
720depends on the driver. The currently defined VBI format types
721are:</entry>
722 </row>
723 <row>
724 <entrytbl spanname="descr" cols="2">
725 <tbody valign="top">
726 <row>
727 <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_NONE</constant>&nbsp;</entry>
728 <entry>No VBI in the MPEG stream</entry>
729 </row>
730 <row>
731 <entry><constant>V4L2_MPEG_STREAM_VBI_FMT_IVTV</constant>&nbsp;</entry>
732 <entry>VBI in private packets, IVTV format (documented
733in the kernel sources in the file <filename>Documentation/video4linux/cx2341x/README.vbi</filename>)</entry>
734 </row>
735 </tbody>
736 </entrytbl>
737 </row>
738 <row><entry></entry></row>
739 <row id="v4l2-mpeg-audio-sampling-freq">
740 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ</constant>&nbsp;</entry>
741 <entry>enum&nbsp;v4l2_mpeg_audio_sampling_freq</entry>
742 </row><row><entry spanname="descr">MPEG Audio sampling
743frequency. Possible values are:</entry>
744 </row>
745 <row>
746 <entrytbl spanname="descr" cols="2">
747 <tbody valign="top">
748 <row>
749 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100</constant>&nbsp;</entry>
750 <entry>44.1 kHz</entry>
751 </row>
752 <row>
753 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000</constant>&nbsp;</entry>
754 <entry>48 kHz</entry>
755 </row>
756 <row>
757 <entry><constant>V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000</constant>&nbsp;</entry>
758 <entry>32 kHz</entry>
759 </row>
760 </tbody>
761 </entrytbl>
762 </row>
763 <row><entry></entry></row>
764 <row id="v4l2-mpeg-audio-encoding">
765 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_ENCODING</constant>&nbsp;</entry>
766 <entry>enum&nbsp;v4l2_mpeg_audio_encoding</entry>
767 </row><row><entry spanname="descr">MPEG Audio encoding.
768Possible values are:</entry>
769 </row>
770 <row>
771 <entrytbl spanname="descr" cols="2">
772 <tbody valign="top">
773 <row>
774 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_1</constant>&nbsp;</entry>
775 <entry>MPEG-1/2 Layer I encoding</entry>
776 </row>
777 <row>
778 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_2</constant>&nbsp;</entry>
779 <entry>MPEG-1/2 Layer II encoding</entry>
780 </row>
781 <row>
782 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_LAYER_3</constant>&nbsp;</entry>
783 <entry>MPEG-1/2 Layer III encoding</entry>
784 </row>
785 <row>
786 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant>&nbsp;</entry>
787 <entry>MPEG-2/4 AAC (Advanced Audio Coding)</entry>
788 </row>
789 <row>
790 <entry><constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant>&nbsp;</entry>
791 <entry>AC-3 aka ATSC A/52 encoding</entry>
792 </row>
793 </tbody>
794 </entrytbl>
795 </row>
796 <row><entry></entry></row>
797 <row id="v4l2-mpeg-audio-l1-bitrate">
798 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L1_BITRATE</constant>&nbsp;</entry>
799 <entry>enum&nbsp;v4l2_mpeg_audio_l1_bitrate</entry>
800 </row><row><entry spanname="descr">MPEG-1/2 Layer I bitrate.
801Possible values are:</entry>
802 </row>
803 <row>
804 <entrytbl spanname="descr" cols="2">
805 <tbody valign="top">
806 <row>
807 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_32K</constant>&nbsp;</entry>
808 <entry>32 kbit/s</entry></row>
809 <row>
810 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_64K</constant>&nbsp;</entry>
811 <entry>64 kbit/s</entry>
812 </row>
813 <row>
814 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_96K</constant>&nbsp;</entry>
815 <entry>96 kbit/s</entry>
816 </row>
817 <row>
818 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_128K</constant>&nbsp;</entry>
819 <entry>128 kbit/s</entry>
820 </row>
821 <row>
822 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_160K</constant>&nbsp;</entry>
823 <entry>160 kbit/s</entry>
824 </row>
825 <row>
826 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_192K</constant>&nbsp;</entry>
827 <entry>192 kbit/s</entry>
828 </row>
829 <row>
830 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_224K</constant>&nbsp;</entry>
831 <entry>224 kbit/s</entry>
832 </row>
833 <row>
834 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_256K</constant>&nbsp;</entry>
835 <entry>256 kbit/s</entry>
836 </row>
837 <row>
838 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_288K</constant>&nbsp;</entry>
839 <entry>288 kbit/s</entry>
840 </row>
841 <row>
842 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_320K</constant>&nbsp;</entry>
843 <entry>320 kbit/s</entry>
844 </row>
845 <row>
846 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_352K</constant>&nbsp;</entry>
847 <entry>352 kbit/s</entry>
848 </row>
849 <row>
850 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_384K</constant>&nbsp;</entry>
851 <entry>384 kbit/s</entry>
852 </row>
853 <row>
854 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_416K</constant>&nbsp;</entry>
855 <entry>416 kbit/s</entry>
856 </row>
857 <row>
858 <entry><constant>V4L2_MPEG_AUDIO_L1_BITRATE_448K</constant>&nbsp;</entry>
859 <entry>448 kbit/s</entry>
860 </row>
861 </tbody>
862 </entrytbl>
863 </row>
864 <row><entry></entry></row>
865 <row id="v4l2-mpeg-audio-l2-bitrate">
866 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L2_BITRATE</constant>&nbsp;</entry>
867 <entry>enum&nbsp;v4l2_mpeg_audio_l2_bitrate</entry>
868 </row><row><entry spanname="descr">MPEG-1/2 Layer II bitrate.
869Possible values are:</entry>
870 </row>
871 <row>
872 <entrytbl spanname="descr" cols="2">
873 <tbody valign="top">
874 <row>
875 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_32K</constant>&nbsp;</entry>
876 <entry>32 kbit/s</entry>
877 </row>
878 <row>
879 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_48K</constant>&nbsp;</entry>
880 <entry>48 kbit/s</entry>
881 </row>
882 <row>
883 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_56K</constant>&nbsp;</entry>
884 <entry>56 kbit/s</entry>
885 </row>
886 <row>
887 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_64K</constant>&nbsp;</entry>
888 <entry>64 kbit/s</entry>
889 </row>
890 <row>
891 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_80K</constant>&nbsp;</entry>
892 <entry>80 kbit/s</entry>
893 </row>
894 <row>
895 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_96K</constant>&nbsp;</entry>
896 <entry>96 kbit/s</entry>
897 </row>
898 <row>
899 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_112K</constant>&nbsp;</entry>
900 <entry>112 kbit/s</entry>
901 </row>
902 <row>
903 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_128K</constant>&nbsp;</entry>
904 <entry>128 kbit/s</entry>
905 </row>
906 <row>
907 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_160K</constant>&nbsp;</entry>
908 <entry>160 kbit/s</entry>
909 </row>
910 <row>
911 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_192K</constant>&nbsp;</entry>
912 <entry>192 kbit/s</entry>
913 </row>
914 <row>
915 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_224K</constant>&nbsp;</entry>
916 <entry>224 kbit/s</entry>
917 </row>
918 <row>
919 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_256K</constant>&nbsp;</entry>
920 <entry>256 kbit/s</entry>
921 </row>
922 <row>
923 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_320K</constant>&nbsp;</entry>
924 <entry>320 kbit/s</entry>
925 </row>
926 <row>
927 <entry><constant>V4L2_MPEG_AUDIO_L2_BITRATE_384K</constant>&nbsp;</entry>
928 <entry>384 kbit/s</entry>
929 </row>
930 </tbody>
931 </entrytbl>
932 </row>
933 <row><entry></entry></row>
934 <row id="v4l2-mpeg-audio-l3-bitrate">
935 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_L3_BITRATE</constant>&nbsp;</entry>
936 <entry>enum&nbsp;v4l2_mpeg_audio_l3_bitrate</entry>
937 </row><row><entry spanname="descr">MPEG-1/2 Layer III bitrate.
938Possible values are:</entry>
939 </row>
940 <row>
941 <entrytbl spanname="descr" cols="2">
942 <tbody valign="top">
943 <row>
944 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_32K</constant>&nbsp;</entry>
945 <entry>32 kbit/s</entry>
946 </row>
947 <row>
948 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_40K</constant>&nbsp;</entry>
949 <entry>40 kbit/s</entry>
950 </row>
951 <row>
952 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_48K</constant>&nbsp;</entry>
953 <entry>48 kbit/s</entry>
954 </row>
955 <row>
956 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_56K</constant>&nbsp;</entry>
957 <entry>56 kbit/s</entry>
958 </row>
959 <row>
960 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_64K</constant>&nbsp;</entry>
961 <entry>64 kbit/s</entry>
962 </row>
963 <row>
964 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_80K</constant>&nbsp;</entry>
965 <entry>80 kbit/s</entry>
966 </row>
967 <row>
968 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_96K</constant>&nbsp;</entry>
969 <entry>96 kbit/s</entry>
970 </row>
971 <row>
972 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_112K</constant>&nbsp;</entry>
973 <entry>112 kbit/s</entry>
974 </row>
975 <row>
976 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_128K</constant>&nbsp;</entry>
977 <entry>128 kbit/s</entry>
978 </row>
979 <row>
980 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_160K</constant>&nbsp;</entry>
981 <entry>160 kbit/s</entry>
982 </row>
983 <row>
984 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_192K</constant>&nbsp;</entry>
985 <entry>192 kbit/s</entry>
986 </row>
987 <row>
988 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_224K</constant>&nbsp;</entry>
989 <entry>224 kbit/s</entry>
990 </row>
991 <row>
992 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_256K</constant>&nbsp;</entry>
993 <entry>256 kbit/s</entry>
994 </row>
995 <row>
996 <entry><constant>V4L2_MPEG_AUDIO_L3_BITRATE_320K</constant>&nbsp;</entry>
997 <entry>320 kbit/s</entry>
998 </row>
999 </tbody>
1000 </entrytbl>
1001 </row>
1002 <row><entry></entry></row>
1003 <row>
1004 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AAC_BITRATE</constant>&nbsp;</entry>
1005 <entry>integer</entry>
1006 </row><row><entry spanname="descr">AAC bitrate in bits per second.</entry>
1007 </row>
1008 <row><entry></entry></row>
1009 <row id="v4l2-mpeg-audio-ac3-bitrate">
1010 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_AC3_BITRATE</constant>&nbsp;</entry>
1011 <entry>enum&nbsp;v4l2_mpeg_audio_ac3_bitrate</entry>
1012 </row><row><entry spanname="descr">AC-3 bitrate.
1013Possible values are:</entry>
1014 </row>
1015 <row>
1016 <entrytbl spanname="descr" cols="2">
1017 <tbody valign="top">
1018 <row>
1019 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_32K</constant>&nbsp;</entry>
1020 <entry>32 kbit/s</entry>
1021 </row>
1022 <row>
1023 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_40K</constant>&nbsp;</entry>
1024 <entry>40 kbit/s</entry>
1025 </row>
1026 <row>
1027 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_48K</constant>&nbsp;</entry>
1028 <entry>48 kbit/s</entry>
1029 </row>
1030 <row>
1031 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_56K</constant>&nbsp;</entry>
1032 <entry>56 kbit/s</entry>
1033 </row>
1034 <row>
1035 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_64K</constant>&nbsp;</entry>
1036 <entry>64 kbit/s</entry>
1037 </row>
1038 <row>
1039 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_80K</constant>&nbsp;</entry>
1040 <entry>80 kbit/s</entry>
1041 </row>
1042 <row>
1043 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_96K</constant>&nbsp;</entry>
1044 <entry>96 kbit/s</entry>
1045 </row>
1046 <row>
1047 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_112K</constant>&nbsp;</entry>
1048 <entry>112 kbit/s</entry>
1049 </row>
1050 <row>
1051 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_128K</constant>&nbsp;</entry>
1052 <entry>128 kbit/s</entry>
1053 </row>
1054 <row>
1055 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_160K</constant>&nbsp;</entry>
1056 <entry>160 kbit/s</entry>
1057 </row>
1058 <row>
1059 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_192K</constant>&nbsp;</entry>
1060 <entry>192 kbit/s</entry>
1061 </row>
1062 <row>
1063 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_224K</constant>&nbsp;</entry>
1064 <entry>224 kbit/s</entry>
1065 </row>
1066 <row>
1067 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_256K</constant>&nbsp;</entry>
1068 <entry>256 kbit/s</entry>
1069 </row>
1070 <row>
1071 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_320K</constant>&nbsp;</entry>
1072 <entry>320 kbit/s</entry>
1073 </row>
1074 <row>
1075 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_384K</constant>&nbsp;</entry>
1076 <entry>384 kbit/s</entry>
1077 </row>
1078 <row>
1079 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_448K</constant>&nbsp;</entry>
1080 <entry>448 kbit/s</entry>
1081 </row>
1082 <row>
1083 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_512K</constant>&nbsp;</entry>
1084 <entry>512 kbit/s</entry>
1085 </row>
1086 <row>
1087 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_576K</constant>&nbsp;</entry>
1088 <entry>576 kbit/s</entry>
1089 </row>
1090 <row>
1091 <entry><constant>V4L2_MPEG_AUDIO_AC3_BITRATE_640K</constant>&nbsp;</entry>
1092 <entry>640 kbit/s</entry>
1093 </row>
1094 </tbody>
1095 </entrytbl>
1096 </row>
1097 <row><entry></entry></row>
1098 <row id="v4l2-mpeg-audio-mode">
1099 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE</constant>&nbsp;</entry>
1100 <entry>enum&nbsp;v4l2_mpeg_audio_mode</entry>
1101 </row><row><entry spanname="descr">MPEG Audio mode.
1102Possible values are:</entry>
1103 </row>
1104 <row>
1105 <entrytbl spanname="descr" cols="2">
1106 <tbody valign="top">
1107 <row>
1108 <entry><constant>V4L2_MPEG_AUDIO_MODE_STEREO</constant>&nbsp;</entry>
1109 <entry>Stereo</entry>
1110 </row>
1111 <row>
1112 <entry><constant>V4L2_MPEG_AUDIO_MODE_JOINT_STEREO</constant>&nbsp;</entry>
1113 <entry>Joint Stereo</entry>
1114 </row>
1115 <row>
1116 <entry><constant>V4L2_MPEG_AUDIO_MODE_DUAL</constant>&nbsp;</entry>
1117 <entry>Bilingual</entry>
1118 </row>
1119 <row>
1120 <entry><constant>V4L2_MPEG_AUDIO_MODE_MONO</constant>&nbsp;</entry>
1121 <entry>Mono</entry>
1122 </row>
1123 </tbody>
1124 </entrytbl>
1125 </row>
1126 <row><entry></entry></row>
1127 <row id="v4l2-mpeg-audio-mode-extension">
1128 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MODE_EXTENSION</constant>&nbsp;</entry>
1129 <entry>enum&nbsp;v4l2_mpeg_audio_mode_extension</entry>
1130 </row><row><entry spanname="descr">Joint Stereo
1131audio mode extension. In Layer I and II they indicate which subbands
1132are in intensity stereo. All other subbands are coded in stereo. Layer
1133III is not (yet) supported. Possible values
1134are:</entry>
1135 </row>
1136 <row>
1137 <entrytbl spanname="descr" cols="2">
1138 <tbody valign="top">
1139 <row>
1140 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4</constant>&nbsp;</entry>
1141 <entry>Subbands 4-31 in intensity stereo</entry>
1142 </row>
1143 <row>
1144 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8</constant>&nbsp;</entry>
1145 <entry>Subbands 8-31 in intensity stereo</entry>
1146 </row>
1147 <row>
1148 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12</constant>&nbsp;</entry>
1149 <entry>Subbands 12-31 in intensity stereo</entry>
1150 </row>
1151 <row>
1152 <entry><constant>V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16</constant>&nbsp;</entry>
1153 <entry>Subbands 16-31 in intensity stereo</entry>
1154 </row>
1155 </tbody>
1156 </entrytbl>
1157 </row>
1158 <row><entry></entry></row>
1159 <row id="v4l2-mpeg-audio-emphasis">
1160 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_EMPHASIS</constant>&nbsp;</entry>
1161 <entry>enum&nbsp;v4l2_mpeg_audio_emphasis</entry>
1162 </row><row><entry spanname="descr">Audio Emphasis.
1163Possible values are:</entry>
1164 </row>
1165 <row>
1166 <entrytbl spanname="descr" cols="2">
1167 <tbody valign="top">
1168 <row>
1169 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_NONE</constant>&nbsp;</entry>
1170 <entry>None</entry>
1171 </row>
1172 <row>
1173 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS</constant>&nbsp;</entry>
1174 <entry>50/15 microsecond emphasis</entry>
1175 </row>
1176 <row>
1177 <entry><constant>V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17</constant>&nbsp;</entry>
1178 <entry>CCITT J.17</entry>
1179 </row>
1180 </tbody>
1181 </entrytbl>
1182 </row>
1183 <row><entry></entry></row>
1184 <row id="v4l2-mpeg-audio-crc">
1185 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_CRC</constant>&nbsp;</entry>
1186 <entry>enum&nbsp;v4l2_mpeg_audio_crc</entry>
1187 </row><row><entry spanname="descr">CRC method. Possible
1188values are:</entry>
1189 </row>
1190 <row>
1191 <entrytbl spanname="descr" cols="2">
1192 <tbody valign="top">
1193 <row>
1194 <entry><constant>V4L2_MPEG_AUDIO_CRC_NONE</constant>&nbsp;</entry>
1195 <entry>None</entry>
1196 </row>
1197 <row>
1198 <entry><constant>V4L2_MPEG_AUDIO_CRC_CRC16</constant>&nbsp;</entry>
1199 <entry>16 bit parity check</entry>
1200 </row>
1201 </tbody>
1202 </entrytbl>
1203 </row>
1204 <row><entry></entry></row>
1205 <row>
1206 <entry spanname="id"><constant>V4L2_CID_MPEG_AUDIO_MUTE</constant>&nbsp;</entry>
1207 <entry>boolean</entry>
1208 </row><row><entry spanname="descr">Mutes the audio when
1209capturing. This is not done by muting audio hardware, which can still
1210produce a slight hiss, but in the encoder itself, guaranteeing a fixed
1211and reproducable audio bitstream. 0 = unmuted, 1 = muted.</entry>
1212 </row>
1213 <row><entry></entry></row>
1214 <row id="v4l2-mpeg-video-encoding">
1215 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ENCODING</constant>&nbsp;</entry>
1216 <entry>enum&nbsp;v4l2_mpeg_video_encoding</entry>
1217 </row><row><entry spanname="descr">MPEG Video encoding
1218method. Possible values are:</entry>
1219 </row>
1220 <row>
1221 <entrytbl spanname="descr" cols="2">
1222 <tbody valign="top">
1223 <row>
1224 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_1</constant>&nbsp;</entry>
1225 <entry>MPEG-1 Video encoding</entry>
1226 </row>
1227 <row>
1228 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_2</constant>&nbsp;</entry>
1229 <entry>MPEG-2 Video encoding</entry>
1230 </row>
1231 <row>
1232 <entry><constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant>&nbsp;</entry>
1233 <entry>MPEG-4 AVC (H.264) Video encoding</entry>
1234 </row>
1235 </tbody>
1236 </entrytbl>
1237 </row>
1238 <row><entry></entry></row>
1239 <row id="v4l2-mpeg-video-aspect">
1240 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_ASPECT</constant>&nbsp;</entry>
1241 <entry>enum&nbsp;v4l2_mpeg_video_aspect</entry>
1242 </row><row><entry spanname="descr">Video aspect.
1243Possible values are:</entry>
1244 </row>
1245 <row>
1246 <entrytbl spanname="descr" cols="2">
1247 <tbody valign="top">
1248 <row>
1249 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_1x1</constant>&nbsp;</entry>
1250 </row>
1251 <row>
1252 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_4x3</constant>&nbsp;</entry>
1253 </row>
1254 <row>
1255 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_16x9</constant>&nbsp;</entry>
1256 </row>
1257 <row>
1258 <entry><constant>V4L2_MPEG_VIDEO_ASPECT_221x100</constant>&nbsp;</entry>
1259 </row>
1260 </tbody>
1261 </entrytbl>
1262 </row>
1263 <row><entry></entry></row>
1264 <row>
1265 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_B_FRAMES</constant>&nbsp;</entry>
1266 <entry>integer</entry>
1267 </row><row><entry spanname="descr">Number of B-Frames
1268(default 2)</entry>
1269 </row>
1270 <row><entry></entry></row>
1271 <row>
1272 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_SIZE</constant>&nbsp;</entry>
1273 <entry>integer</entry>
1274 </row><row><entry spanname="descr">GOP size (default
127512)</entry>
1276 </row>
1277 <row><entry></entry></row>
1278 <row>
1279 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_GOP_CLOSURE</constant>&nbsp;</entry>
1280 <entry>boolean</entry>
1281 </row><row><entry spanname="descr">GOP closure (default
12821)</entry>
1283 </row>
1284 <row><entry></entry></row>
1285 <row>
1286 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_PULLDOWN</constant>&nbsp;</entry>
1287 <entry>boolean</entry>
1288 </row><row><entry spanname="descr">Enable 3:2 pulldown
1289(default 0)</entry>
1290 </row>
1291 <row><entry></entry></row>
1292 <row id="v4l2-mpeg-video-bitrate-mode">
1293 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_MODE</constant>&nbsp;</entry>
1294 <entry>enum&nbsp;v4l2_mpeg_video_bitrate_mode</entry>
1295 </row><row><entry spanname="descr">Video bitrate mode.
1296Possible values are:</entry>
1297 </row>
1298 <row>
1299 <entrytbl spanname="descr" cols="2">
1300 <tbody valign="top">
1301 <row>
1302 <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_VBR</constant>&nbsp;</entry>
1303 <entry>Variable bitrate</entry>
1304 </row>
1305 <row>
1306 <entry><constant>V4L2_MPEG_VIDEO_BITRATE_MODE_CBR</constant>&nbsp;</entry>
1307 <entry>Constant bitrate</entry>
1308 </row>
1309 </tbody>
1310 </entrytbl>
1311 </row>
1312 <row><entry></entry></row>
1313 <row>
1314 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE</constant>&nbsp;</entry>
1315 <entry>integer</entry>
1316 </row><row><entry spanname="descr">Video bitrate in bits
1317per second.</entry>
1318 </row>
1319 <row><entry></entry></row>
1320 <row>
1321 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_BITRATE_PEAK</constant>&nbsp;</entry>
1322 <entry>integer</entry>
1323 </row><row><entry spanname="descr">Peak video bitrate in
1324bits per second. Must be larger or equal to the average video bitrate.
1325It is ignored if the video bitrate mode is set to constant
1326bitrate.</entry>
1327 </row>
1328 <row><entry></entry></row>
1329 <row>
1330 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION</constant>&nbsp;</entry>
1331 <entry>integer</entry>
1332 </row><row><entry spanname="descr">For every captured
1333frame, skip this many subsequent frames (default 0).</entry>
1334 </row>
1335 <row><entry></entry></row>
1336 <row>
1337 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE</constant>&nbsp;</entry>
1338 <entry>boolean</entry>
1339 </row>
1340 <row><entry spanname="descr">"Mutes" the video to a
1341fixed color when capturing. This is useful for testing, to produce a
1342fixed video bitstream. 0 = unmuted, 1 = muted.</entry>
1343 </row>
1344 <row><entry></entry></row>
1345 <row>
1346 <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_MUTE_YUV</constant>&nbsp;</entry>
1347 <entry>integer</entry>
1348 </row><row><entry spanname="descr">Sets the "mute" color
1349of the video. The supplied 32-bit integer is interpreted as follows (bit
13500 = least significant bit):</entry>
1351 </row>
1352 <row>
1353 <entrytbl spanname="descr" cols="2">
1354 <tbody valign="top">
1355 <row>
1356 <entry>Bit 0:7</entry>
1357 <entry>V chrominance information</entry>
1358 </row>
1359 <row>
1360 <entry>Bit 8:15</entry>
1361 <entry>U chrominance information</entry>
1362 </row>
1363 <row>
1364 <entry>Bit 16:23</entry>
1365 <entry>Y luminance information</entry>
1366 </row>
1367 <row>
1368 <entry>Bit 24:31</entry>
1369 <entry>Must be zero.</entry>
1370 </row>
1371 </tbody>
1372 </entrytbl>
1373 </row>
1374 </tbody>
1375 </tgroup>
1376 </table>
1377 </section>
1378
1379 <section>
1380 <title>CX2341x MPEG Controls</title>
1381
1382 <para>The following MPEG class controls deal with MPEG
1383encoding settings that are specific to the Conexant CX23415 and
1384CX23416 MPEG encoding chips.</para>
1385
1386 <table pgwide="1" frame="none" id="cx2341x-control-id">
1387 <title>CX2341x Control IDs</title>
1388 <tgroup cols="4">
1389 <colspec colname="c1" colwidth="1*" />
1390 <colspec colname="c2" colwidth="6*" />
1391 <colspec colname="c3" colwidth="2*" />
1392 <colspec colname="c4" colwidth="6*" />
1393 <spanspec namest="c1" nameend="c2" spanname="id" />
1394 <spanspec namest="c2" nameend="c4" spanname="descr" />
1395 <thead>
1396 <row>
1397 <entry spanname="id" align="left">ID</entry>
1398 <entry align="left">Type</entry>
1399 </row><row><entry spanname="descr" align="left">Description</entry>
1400 </row>
1401 </thead>
1402 <tbody valign="top">
1403 <row><entry></entry></row>
1404 <row id="v4l2-mpeg-cx2341x-video-spatial-filter-mode">
1405 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE</constant>&nbsp;</entry>
1406 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_spatial_filter_mode</entry>
1407 </row><row><entry spanname="descr">Sets the Spatial
1408Filter mode (default <constant>MANUAL</constant>). Possible values
1409are:</entry>
1410 </row>
1411 <row>
1412 <entrytbl spanname="descr" cols="2">
1413 <tbody valign="top">
1414 <row>
1415 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL</constant>&nbsp;</entry>
1416 <entry>Choose the filter manually</entry>
1417 </row>
1418 <row>
1419 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO</constant>&nbsp;</entry>
1420 <entry>Choose the filter automatically</entry>
1421 </row>
1422 </tbody>
1423 </entrytbl>
1424 </row>
1425 <row><entry></entry></row>
1426 <row>
1427 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER</constant>&nbsp;</entry>
1428 <entry>integer&nbsp;(0-15)</entry>
1429 </row><row><entry spanname="descr">The setting for the
1430Spatial Filter. 0 = off, 15 = maximum. (Default is 0.)</entry>
1431 </row>
1432 <row><entry></entry></row>
1433 <row id="luma-spatial-filter-type">
1434 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE</constant>&nbsp;</entry>
1435 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_luma_spatial_filter_type</entry>
1436 </row><row><entry spanname="descr">Select the algorithm
1437to use for the Luma Spatial Filter (default
1438<constant>1D_HOR</constant>). Possible values:</entry>
1439 </row>
1440 <row>
1441 <entrytbl spanname="descr" cols="2">
1442 <tbody valign="top">
1443 <row>
1444 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF</constant>&nbsp;</entry>
1445 <entry>No filter</entry>
1446 </row>
1447 <row>
1448 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR</constant>&nbsp;</entry>
1449 <entry>One-dimensional horizontal</entry>
1450 </row>
1451 <row>
1452 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT</constant>&nbsp;</entry>
1453 <entry>One-dimensional vertical</entry>
1454 </row>
1455 <row>
1456 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE</constant>&nbsp;</entry>
1457 <entry>Two-dimensional separable</entry>
1458 </row>
1459 <row>
1460 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE</constant>&nbsp;</entry>
1461 <entry>Two-dimensional symmetrical
1462non-separable</entry>
1463 </row>
1464 </tbody>
1465 </entrytbl>
1466 </row>
1467 <row><entry></entry></row>
1468 <row id="chroma-spatial-filter-type">
1469 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE</constant>&nbsp;</entry>
1470 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type</entry>
1471 </row><row><entry spanname="descr">Select the algorithm
1472for the Chroma Spatial Filter (default <constant>1D_HOR</constant>).
1473Possible values are:</entry>
1474 </row>
1475 <row>
1476 <entrytbl spanname="descr" cols="2">
1477 <tbody valign="top">
1478 <row>
1479 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF</constant>&nbsp;</entry>
1480 <entry>No filter</entry>
1481 </row>
1482 <row>
1483 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR</constant>&nbsp;</entry>
1484 <entry>One-dimensional horizontal</entry>
1485 </row>
1486 </tbody>
1487 </entrytbl>
1488 </row>
1489 <row><entry></entry></row>
1490 <row id="v4l2-mpeg-cx2341x-video-temporal-filter-mode">
1491 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE</constant>&nbsp;</entry>
1492 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_temporal_filter_mode</entry>
1493 </row><row><entry spanname="descr">Sets the Temporal
1494Filter mode (default <constant>MANUAL</constant>). Possible values
1495are:</entry>
1496 </row>
1497 <row>
1498 <entrytbl spanname="descr" cols="2">
1499 <tbody valign="top">
1500 <row>
1501 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL</constant>&nbsp;</entry>
1502 <entry>Choose the filter manually</entry>
1503 </row>
1504 <row>
1505 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO</constant>&nbsp;</entry>
1506 <entry>Choose the filter automatically</entry>
1507 </row>
1508 </tbody>
1509 </entrytbl>
1510 </row>
1511 <row><entry></entry></row>
1512 <row>
1513 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER</constant>&nbsp;</entry>
1514 <entry>integer&nbsp;(0-31)</entry>
1515 </row><row><entry spanname="descr">The setting for the
1516Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale
1517capturing and 0 for scaled capturing.)</entry>
1518 </row>
1519 <row><entry></entry></row>
1520 <row id="v4l2-mpeg-cx2341x-video-median-filter-type">
1521 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE</constant>&nbsp;</entry>
1522 <entry>enum&nbsp;v4l2_mpeg_cx2341x_video_median_filter_type</entry>
1523 </row><row><entry spanname="descr">Median Filter Type
1524(default <constant>OFF</constant>). Possible values are:</entry>
1525 </row>
1526 <row>
1527 <entrytbl spanname="descr" cols="2">
1528 <tbody valign="top">
1529 <row>
1530 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF</constant>&nbsp;</entry>
1531 <entry>No filter</entry>
1532 </row>
1533 <row>
1534 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR</constant>&nbsp;</entry>
1535 <entry>Horizontal filter</entry>
1536 </row>
1537 <row>
1538 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT</constant>&nbsp;</entry>
1539 <entry>Vertical filter</entry>
1540 </row>
1541 <row>
1542 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT</constant>&nbsp;</entry>
1543 <entry>Horizontal and vertical filter</entry>
1544 </row>
1545 <row>
1546 <entry><constant>V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG</constant>&nbsp;</entry>
1547 <entry>Diagonal filter</entry>
1548 </row>
1549 </tbody>
1550 </entrytbl>
1551 </row>
1552 <row><entry></entry></row>
1553 <row>
1554 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM</constant>&nbsp;</entry>
1555 <entry>integer&nbsp;(0-255)</entry>
1556 </row><row><entry spanname="descr">Threshold above which
1557the luminance median filter is enabled (default 0)</entry>
1558 </row>
1559 <row><entry></entry></row>
1560 <row>
1561 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP</constant>&nbsp;</entry>
1562 <entry>integer&nbsp;(0-255)</entry>
1563 </row><row><entry spanname="descr">Threshold below which
1564the luminance median filter is enabled (default 255)</entry>
1565 </row>
1566 <row><entry></entry></row>
1567 <row>
1568 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM</constant>&nbsp;</entry>
1569 <entry>integer&nbsp;(0-255)</entry>
1570 </row><row><entry spanname="descr">Threshold above which
1571the chroma median filter is enabled (default 0)</entry>
1572 </row>
1573 <row><entry></entry></row>
1574 <row>
1575 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP</constant>&nbsp;</entry>
1576 <entry>integer&nbsp;(0-255)</entry>
1577 </row><row><entry spanname="descr">Threshold below which
1578the chroma median filter is enabled (default 255)</entry>
1579 </row>
1580 <row><entry></entry></row>
1581 <row>
1582 <entry spanname="id"><constant>V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS</constant>&nbsp;</entry>
1583 <entry>boolean</entry>
1584 </row>
1585 <row><entry spanname="descr">The CX2341X MPEG encoder
1586can insert one empty MPEG-2 PES packet into the stream between every
1587four video frames. The packet size is 2048 bytes, including the
1588packet_start_code_prefix and stream_id fields. The stream_id is 0xBF
1589(private stream 2). The payload consists of 0x00 bytes, to be filled
1590in by the application. 0 = do not insert, 1 = insert packets.</entry>
1591 </row>
1592 </tbody>
1593 </tgroup>
1594 </table>
1595 </section>
1596 </section>
1597
1598 <section id="camera-controls">
1599 <title>Camera Control Reference</title>
1600
1601 <para>The Camera class includes controls for mechanical (or
1602equivalent digital) features of a device such as controllable lenses
1603or sensors.</para>
1604
1605 <table pgwide="1" frame="none" id="camera-control-id">
1606 <title>Camera Control IDs</title>
1607 <tgroup cols="4">
1608 <colspec colname="c1" colwidth="1*" />
1609 <colspec colname="c2" colwidth="6*" />
1610 <colspec colname="c3" colwidth="2*" />
1611 <colspec colname="c4" colwidth="6*" />
1612 <spanspec namest="c1" nameend="c2" spanname="id" />
1613 <spanspec namest="c2" nameend="c4" spanname="descr" />
1614 <thead>
1615 <row>
1616 <entry spanname="id" align="left">ID</entry>
1617 <entry align="left">Type</entry>
1618 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
1619 </row>
1620 </thead>
1621 <tbody valign="top">
1622 <row><entry></entry></row>
1623 <row>
1624 <entry spanname="id"><constant>V4L2_CID_CAMERA_CLASS</constant>&nbsp;</entry>
1625 <entry>class</entry>
1626 </row><row><entry spanname="descr">The Camera class
1627descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
1628description of this control class.</entry>
1629 </row>
1630 <row><entry></entry></row>
1631
1632 <row id="v4l2-exposure-auto-type">
1633 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO</constant>&nbsp;</entry>
1634 <entry>enum&nbsp;v4l2_exposure_auto_type</entry>
1635 </row><row><entry spanname="descr">Enables automatic
1636adjustments of the exposure time and/or iris aperture. The effect of
1637manual changes of the exposure time or iris aperture while these
1638features are enabled is undefined, drivers should ignore such
1639requests. Possible values are:</entry>
1640 </row>
1641 <row>
1642 <entrytbl spanname="descr" cols="2">
1643 <tbody valign="top">
1644 <row>
1645 <entry><constant>V4L2_EXPOSURE_AUTO</constant>&nbsp;</entry>
1646 <entry>Automatic exposure time, automatic iris
1647aperture.</entry>
1648 </row>
1649 <row>
1650 <entry><constant>V4L2_EXPOSURE_MANUAL</constant>&nbsp;</entry>
1651 <entry>Manual exposure time, manual iris.</entry>
1652 </row>
1653 <row>
1654 <entry><constant>V4L2_EXPOSURE_SHUTTER_PRIORITY</constant>&nbsp;</entry>
1655 <entry>Manual exposure time, auto iris.</entry>
1656 </row>
1657 <row>
1658 <entry><constant>V4L2_EXPOSURE_APERTURE_PRIORITY</constant>&nbsp;</entry>
1659 <entry>Auto exposure time, manual iris.</entry>
1660 </row>
1661 </tbody>
1662 </entrytbl>
1663 </row>
1664 <row><entry></entry></row>
1665
1666 <row>
1667 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant>&nbsp;</entry>
1668 <entry>integer</entry>
1669 </row><row><entry spanname="descr">Determines the exposure
1670time of the camera sensor. The exposure time is limited by the frame
1671interval. Drivers should interpret the values as 100 &micro;s units,
1672where the value 1 stands for 1/10000th of a second, 10000 for 1 second
1673and 100000 for 10 seconds.</entry>
1674 </row>
1675 <row><entry></entry></row>
1676
1677 <row>
1678 <entry spanname="id"><constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant>&nbsp;</entry>
1679 <entry>boolean</entry>
1680 </row><row><entry spanname="descr">When
1681<constant>V4L2_CID_EXPOSURE_AUTO</constant> is set to
1682<constant>AUTO</constant> or <constant>APERTURE_PRIORITY</constant>,
1683this control determines if the device may dynamically vary the frame
1684rate. By default this feature is disabled (0) and the frame rate must
1685remain constant.</entry>
1686 </row>
1687 <row><entry></entry></row>
1688
1689 <row>
1690 <entry spanname="id"><constant>V4L2_CID_PAN_RELATIVE</constant>&nbsp;</entry>
1691 <entry>integer</entry>
1692 </row><row><entry spanname="descr">This control turns the
1693camera horizontally by the specified amount. The unit is undefined. A
1694positive value moves the camera to the right (clockwise when viewed
1695from above), a negative value to the left. A value of zero does not
1696cause motion. This is a write-only control.</entry>
1697 </row>
1698 <row><entry></entry></row>
1699
1700 <row>
1701 <entry spanname="id"><constant>V4L2_CID_TILT_RELATIVE</constant>&nbsp;</entry>
1702 <entry>integer</entry>
1703 </row><row><entry spanname="descr">This control turns the
1704camera vertically by the specified amount. The unit is undefined. A
1705positive value moves the camera up, a negative value down. A value of
1706zero does not cause motion. This is a write-only control.</entry>
1707 </row>
1708 <row><entry></entry></row>
1709
1710 <row>
1711 <entry spanname="id"><constant>V4L2_CID_PAN_RESET</constant>&nbsp;</entry>
1712 <entry>button</entry>
1713 </row><row><entry spanname="descr">When this control is set,
1714the camera moves horizontally to the default position.</entry>
1715 </row>
1716 <row><entry></entry></row>
1717
1718 <row>
1719 <entry spanname="id"><constant>V4L2_CID_TILT_RESET</constant>&nbsp;</entry>
1720 <entry>button</entry>
1721 </row><row><entry spanname="descr">When this control is set,
1722the camera moves vertically to the default position.</entry>
1723 </row>
1724 <row><entry></entry></row>
1725
1726 <row>
1727 <entry spanname="id"><constant>V4L2_CID_PAN_ABSOLUTE</constant>&nbsp;</entry>
1728 <entry>integer</entry>
1729 </row><row><entry spanname="descr">This control
1730turns the camera horizontally to the specified position. Positive
1731values move the camera to the right (clockwise when viewed from above),
1732negative values to the left. Drivers should interpret the values as arc
1733seconds, with valid values between -180 * 3600 and +180 * 3600
1734inclusive.</entry>
1735 </row>
1736 <row><entry></entry></row>
1737
1738 <row>
1739 <entry spanname="id"><constant>V4L2_CID_TILT_ABSOLUTE</constant>&nbsp;</entry>
1740 <entry>integer</entry>
1741 </row><row><entry spanname="descr">This control
1742turns the camera vertically to the specified position. Positive values
1743move the camera up, negative values down. Drivers should interpret the
1744values as arc seconds, with valid values between -180 * 3600 and +180
1745* 3600 inclusive.</entry>
1746 </row>
1747 <row><entry></entry></row>
1748
1749 <row>
1750 <entry spanname="id"><constant>V4L2_CID_FOCUS_ABSOLUTE</constant>&nbsp;</entry>
1751 <entry>integer</entry>
1752 </row><row><entry spanname="descr">This control sets the
1753focal point of the camera to the specified position. The unit is
1754undefined. Positive values set the focus closer to the camera,
1755negative values towards infinity.</entry>
1756 </row>
1757 <row><entry></entry></row>
1758
1759 <row>
1760 <entry spanname="id"><constant>V4L2_CID_FOCUS_RELATIVE</constant>&nbsp;</entry>
1761 <entry>integer</entry>
1762 </row><row><entry spanname="descr">This control moves the
1763focal point of the camera by the specified amount. The unit is
1764undefined. Positive values move the focus closer to the camera,
1765negative values towards infinity. This is a write-only control.</entry>
1766 </row>
1767 <row><entry></entry></row>
1768
1769 <row>
1770 <entry spanname="id"><constant>V4L2_CID_FOCUS_AUTO</constant>&nbsp;</entry>
1771 <entry>boolean</entry>
1772 </row><row><entry spanname="descr">Enables automatic focus
1773adjustments. The effect of manual focus adjustments while this feature
1774is enabled is undefined, drivers should ignore such requests.</entry>
1775 </row>
1776 <row><entry></entry></row>
1777
1778 <row>
1779 <entry spanname="id"><constant>V4L2_CID_ZOOM_ABSOLUTE</constant>&nbsp;</entry>
1780 <entry>integer</entry>
1781 </row><row><entry spanname="descr">Specify the objective lens
1782focal length as an absolute value. The zoom unit is driver-specific and its
1783value should be a positive integer.</entry>
1784 </row>
1785 <row><entry></entry></row>
1786
1787 <row>
1788 <entry spanname="id"><constant>V4L2_CID_ZOOM_RELATIVE</constant>&nbsp;</entry>
1789 <entry>integer</entry>
1790 </row><row><entry spanname="descr">Specify the objective lens
1791focal length relatively to the current value. Positive values move the zoom
1792lens group towards the telephoto direction, negative values towards the
1793wide-angle direction. The zoom unit is driver-specific. This is a write-only control.</entry>
1794 </row>
1795 <row><entry></entry></row>
1796
1797 <row>
1798 <entry spanname="id"><constant>V4L2_CID_ZOOM_CONTINUOUS</constant>&nbsp;</entry>
1799 <entry>integer</entry>
1800 </row><row><entry spanname="descr">Move the objective lens group
1801at the specified speed until it reaches physical device limits or until an
1802explicit request to stop the movement. A positive value moves the zoom lens
1803group towards the telephoto direction. A value of zero stops the zoom lens
1804group movement. A negative value moves the zoom lens group towards the
1805wide-angle direction. The zoom speed unit is driver-specific.</entry>
1806 </row>
1807 <row><entry></entry></row>
1808
1809 <row>
1810 <entry spanname="id"><constant>V4L2_CID_PRIVACY</constant>&nbsp;</entry>
1811 <entry>boolean</entry>
1812 </row><row><entry spanname="descr">Prevent video from being acquired
1813by the camera. When this control is set to <constant>TRUE</constant> (1), no
1814image can be captured by the camera. Common means to enforce privacy are
1815mechanical obturation of the sensor and firmware image processing, but the
1816device is not restricted to these methods. Devices that implement the privacy
1817control must support read access and may support write access.</entry>
1818 </row>
1819
1820 <row>
1821 <entry spanname="id"><constant>V4L2_CID_BAND_STOP_FILTER</constant>&nbsp;</entry>
1822 <entry>integer</entry>
1823 </row><row><entry spanname="descr">Switch the band-stop filter of a
1824camera sensor on or off, or specify its strength. Such band-stop filters can
1825be used, for example, to filter out the fluorescent light component.</entry>
1826 </row>
1827 <row><entry></entry></row>
1828 </tbody>
1829 </tgroup>
1830 </table>
1831 </section>
1832
1833 <section id="fm-tx-controls">
1834 <title>FM Transmitter Control Reference</title>
1835
1836 <para>The FM Transmitter (FM_TX) class includes controls for common features of
1837FM transmissions capable devices. Currently this class includes parameters for audio
1838compression, pilot tone generation, audio deviation limiter, RDS transmission and
1839tuning power features.</para>
1840
1841 <table pgwide="1" frame="none" id="fm-tx-control-id">
1842 <title>FM_TX Control IDs</title>
1843
1844 <tgroup cols="4">
1845 <colspec colname="c1" colwidth="1*" />
1846 <colspec colname="c2" colwidth="6*" />
1847 <colspec colname="c3" colwidth="2*" />
1848 <colspec colname="c4" colwidth="6*" />
1849 <spanspec namest="c1" nameend="c2" spanname="id" />
1850 <spanspec namest="c2" nameend="c4" spanname="descr" />
1851 <thead>
1852 <row>
1853 <entry spanname="id" align="left">ID</entry>
1854 <entry align="left">Type</entry>
1855 </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
1856 </row>
1857 </thead>
1858 <tbody valign="top">
1859 <row><entry></entry></row>
1860 <row>
1861 <entry spanname="id"><constant>V4L2_CID_FM_TX_CLASS</constant>&nbsp;</entry>
1862 <entry>class</entry>
1863 </row><row><entry spanname="descr">The FM_TX class
1864descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
1865description of this control class.</entry>
1866 </row>
1867 <row>
1868 <entry spanname="id"><constant>V4L2_CID_RDS_TX_DEVIATION</constant>&nbsp;</entry>
1869 <entry>integer</entry>
1870 </row>
1871 <row><entry spanname="descr">Configures RDS signal frequency deviation level in Hz.
1872The range and step are driver-specific.</entry>
1873 </row>
1874 <row>
1875 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PI</constant>&nbsp;</entry>
1876 <entry>integer</entry>
1877 </row>
1878 <row><entry spanname="descr">Sets the RDS Programme Identification field
1879for transmission.</entry>
1880 </row>
1881 <row>
1882 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PTY</constant>&nbsp;</entry>
1883 <entry>integer</entry>
1884 </row>
1885 <row><entry spanname="descr">Sets the RDS Programme Type field for transmission.
1886This encodes up to 31 pre-defined programme types.</entry>
1887 </row>
1888 <row>
1889 <entry spanname="id"><constant>V4L2_CID_RDS_TX_PS_NAME</constant>&nbsp;</entry>
1890 <entry>string</entry>
1891 </row>
1892 <row><entry spanname="descr">Sets the Programme Service name (PS_NAME) for transmission.
1893It is intended for static display on a receiver. It is the primary aid to listeners in programme service
1894identification and selection. In Annex E of <xref linkend="en50067" />, the RDS specification,
1895there is a full description of the correct character encoding for Programme Service name strings.
1896Also from RDS specification, PS is usually a single eight character text. However, it is also possible
1897to find receivers which can scroll strings sized as 8 x N characters. So, this control must be configured
1898with steps of 8 characters. The result is it must always contain a string with size multiple of 8.</entry>
1899 </row>
1900 <row>
1901 <entry spanname="id"><constant>V4L2_CID_RDS_TX_RADIO_TEXT</constant>&nbsp;</entry>
1902 <entry>string</entry>
1903 </row>
1904 <row><entry spanname="descr">Sets the Radio Text info for transmission. It is a textual description of
1905what is being broadcasted. RDS Radio Text can be applied when broadcaster wishes to transmit longer PS names,
1906programme-related information or any other text. In these cases, RadioText should be used in addition to
1907<constant>V4L2_CID_RDS_TX_PS_NAME</constant>. The encoding for Radio Text strings is also fully described
1908in Annex E of <xref linkend="en50067" />. The length of Radio Text strings depends on which RDS Block is being
1909used to transmit it, either 32 (2A block) or 64 (2B block). However, it is also possible
1910to find receivers which can scroll strings sized as 32 x N or 64 x N characters. So, this control must be configured
1911with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </entry>
1912 </row>
1913 <row>
1914 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_ENABLED</constant>&nbsp;</entry>
1915 <entry>boolean</entry>
1916 </row>
1917 <row><entry spanname="descr">Enables or disables the audio deviation limiter feature.
1918The limiter is useful when trying to maximize the audio volume, minimize receiver-generated
1919distortion and prevent overmodulation.
1920</entry>
1921 </row>
1922 <row>
1923 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_RELEASE_TIME</constant>&nbsp;</entry>
1924 <entry>integer</entry>
1925 </row>
1926 <row><entry spanname="descr">Sets the audio deviation limiter feature release time.
1927Unit is in useconds. Step and range are driver-specific.</entry>
1928 </row>
1929 <row>
1930 <entry spanname="id"><constant>V4L2_CID_AUDIO_LIMITER_DEVIATION</constant>&nbsp;</entry>
1931 <entry>integer</entry>
1932 </row>
1933 <row><entry spanname="descr">Configures audio frequency deviation level in Hz.
1934The range and step are driver-specific.</entry>
1935 </row>
1936 <row>
1937 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ENABLED</constant>&nbsp;</entry>
1938 <entry>boolean</entry>
1939 </row>
1940 <row><entry spanname="descr">Enables or disables the audio compression feature.
1941This feature amplifies signals below the threshold by a fixed gain and compresses audio
1942signals above the threshold by the ratio of Threshold/(Gain + Threshold).</entry>
1943 </row>
1944 <row>
1945 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_GAIN</constant>&nbsp;</entry>
1946 <entry>integer</entry>
1947 </row>
1948 <row><entry spanname="descr">Sets the gain for audio compression feature. It is
1949a dB value. The range and step are driver-specific.</entry>
1950 </row>
1951 <row>
1952 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_THRESHOLD</constant>&nbsp;</entry>
1953 <entry>integer</entry>
1954 </row>
1955 <row><entry spanname="descr">Sets the threshold level for audio compression freature.
1956It is a dB value. The range and step are driver-specific.</entry>
1957 </row>
1958 <row>
1959 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME</constant>&nbsp;</entry>
1960 <entry>integer</entry>
1961 </row>
1962 <row><entry spanname="descr">Sets the attack time for audio compression feature.
1963It is a useconds value. The range and step are driver-specific.</entry>
1964 </row>
1965 <row>
1966 <entry spanname="id"><constant>V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME</constant>&nbsp;</entry>
1967 <entry>integer</entry>
1968 </row>
1969 <row><entry spanname="descr">Sets the release time for audio compression feature.
1970It is a useconds value. The range and step are driver-specific.</entry>
1971 </row>
1972 <row>
1973 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_ENABLED</constant>&nbsp;</entry>
1974 <entry>boolean</entry>
1975 </row>
1976 <row><entry spanname="descr">Enables or disables the pilot tone generation feature.</entry>
1977 </row>
1978 <row>
1979 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_DEVIATION</constant>&nbsp;</entry>
1980 <entry>integer</entry>
1981 </row>
1982 <row><entry spanname="descr">Configures pilot tone frequency deviation level. Unit is
1983in Hz. The range and step are driver-specific.</entry>
1984 </row>
1985 <row>
1986 <entry spanname="id"><constant>V4L2_CID_PILOT_TONE_FREQUENCY</constant>&nbsp;</entry>
1987 <entry>integer</entry>
1988 </row>
1989 <row><entry spanname="descr">Configures pilot tone frequency value. Unit is
1990in Hz. The range and step are driver-specific.</entry>
1991 </row>
1992 <row>
1993 <entry spanname="id"><constant>V4L2_CID_TUNE_PREEMPHASIS</constant>&nbsp;</entry>
1994 <entry>integer</entry>
1995 </row>
1996 <row id="v4l2-preemphasis"><entry spanname="descr">Configures the pre-emphasis value for broadcasting.
1997A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies.
1998Depending on the region, a time constant of either 50 or 75 useconds is used. The enum&nbsp;v4l2_preemphasis
1999defines possible values for pre-emphasis. Here they are:</entry>
2000 </row><row>
2001 <entrytbl spanname="descr" cols="2">
2002 <tbody valign="top">
2003 <row>
2004 <entry><constant>V4L2_PREEMPHASIS_DISABLED</constant>&nbsp;</entry>
2005 <entry>No pre-emphasis is applied.</entry>
2006 </row>
2007 <row>
2008 <entry><constant>V4L2_PREEMPHASIS_50_uS</constant>&nbsp;</entry>
2009 <entry>A pre-emphasis of 50 uS is used.</entry>
2010 </row>
2011 <row>
2012 <entry><constant>V4L2_PREEMPHASIS_75_uS</constant>&nbsp;</entry>
2013 <entry>A pre-emphasis of 75 uS is used.</entry>
2014 </row>
2015 </tbody>
2016 </entrytbl>
2017
2018 </row>
2019 <row>
2020 <entry spanname="id"><constant>V4L2_CID_TUNE_POWER_LEVEL</constant>&nbsp;</entry>
2021 <entry>integer</entry>
2022 </row>
2023 <row><entry spanname="descr">Sets the output power level for signal transmission.
2024Unit is in dBuV. Range and step are driver-specific.</entry>
2025 </row>
2026 <row>
2027 <entry spanname="id"><constant>V4L2_CID_TUNE_ANTENNA_CAPACITOR</constant>&nbsp;</entry>
2028 <entry>integer</entry>
2029 </row>
2030 <row><entry spanname="descr">This selects the value of antenna tuning capacitor
2031manually or automatically if set to zero. Unit, range and step are driver-specific.</entry>
2032 </row>
2033 <row><entry></entry></row>
2034 </tbody>
2035 </tgroup>
2036 </table>
2037
2038<para>For more details about RDS specification, refer to
2039<xref linkend="en50067" /> document, from CENELEC.</para>
2040 </section>
2041</section>
2042
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